Title: Energy Flux Positivity and Unitarity in CFTs Show Chinese title

Title: 共形场论中的能量流 positivity 和幺正性

Abstract: We show that in most conformal field theories the condition of the energy flux positivity, proposed by Hofman and Maldacena, is equivalent to the absence of ghosts. At finite temperature and large energy and momenta, the two-point functions of the stress energy tensor develop lightlike poles. The residues of the poles can be computed, as long as the only spin two conserved current, which appears in the stress energy tensor OPE and acquires nonvanishing expectation value at finite temperature, is the stress energy tensor. The condition for the residues to stay positive and the theory to remain ghost free is equivalent to the condition of positivity of energy flux. Show Chinese abstract

Abstract: 我们证明，在大多数共形场论中，Hofman 和 Maldacena 提出的能量流正性条件等价于幽灵自由的条件。在有限温度和大能量与动量的情况下，能量-动量张量的两点函数会发展出光锥极点。只要出现在能量-动量张量 OPE 中且在有限温度下获得非零期望值的唯一自旋二守恒流是能量-动量张量本身，就可以计算这些极点的留数。留数保持正值且理论保持无幽灵的条件等价于能量流正性的条件。